If you knead bread by hand, it'll have some human DNA in it from e.g your skin cells. It's almost impossible to cook or process food while preventing it from getting literally any human cells into it, because humans are shedding cells and DNA literally all the time. You can wear gloves, hairnets, and frequently mop up, but eliminating the problem entirely is hard.

Both a vegetarian burger and a beef burger are probably going to have more human DNA in it than either a steak or a pot of black beans would.